Yōga Sūtra 4.19

न तत्स्वाभासं दृश्यत्वात्।

na tatsvābhāsaṁ dr̥śyatvāt।

[न तत् स्वाभासं दृश्यत्वात्।
na = is not; tat = that (chitta); svābhāsaṁ = self-illumined; dr̥śyatvāt = when perceived;]

That (Chitta) is not self-illumined when perceived.